1. Field of the Invention
The present invention relates to a liquid crystal panel manufacturing apparatus, more particularly, to an apparatus for manufacturing a sheet constituting at least one empty liquid crystal cell by adhering a pair of substrates with a thermosetting resin as one process in the manufacture of a liquid crystal display element and, in more detail, to an apparatus for pressing a pair of substrates in the vertical direction with a uniform pressure.
2. Description of the Prior Art
FIG. 1 shows a first conventional liquid crystal panel manufacturing apparatus. According to this first prior art, fixing jigs 32 and 34, respectively, having recesses in their opposing inner surfaces are vertically arranged, and a pair of substrates 31 are clamped between the fixing jigs 32 and 34. A thermosetting resin 42 as an adhesive, which also serves as a spacer, is placed between the pair of substrates 31. A fluid from one supply source (not shown) is supplied to two, upper and lower pressure regions 36 surrounded by the upper and lower outer surfaces, respectively, of the pair of substrates 31 and the two recesses of the fixing jigs 32 and 34. The pair of substrates 31 are pressed against each other with the pressure of this fluid (see Japanese Unexamined Patent Publication No. 6-194618).
In the first prior art described above, the pair of substrates 31 are pressed by the fluid. In a second prior art shown in FIG. 2, pairs of substrates 31 and rubber sheets 44 each having a pressure plate 45 on the substrate side, are alternately stacked in a plurality of stages. A fluid is supplied into the respective rubber sheets 44 to inflate them, thereby pressing the plurality of pairs of substrates 31 (see Japanese Unexamined Patent Publication No. 6-194618). As a result, a uniform air gap can be obtained between each pair of substrates without distorting the substrates 31, while causing no warp in the substrates 31.
As shown in FIG. 3, an apparatus as a modification of the first prior art is also known. In this apparatus, projections 32a and 34a are formed, on surfaces of fixing jigs 32 and 34 that oppose substrates 31, at positions corresponding to a thermosetting resin 42 placed between the pair of substrates 31, to form pressure regions surrounded by the fixing jigs 32 and 34, the pair of substrates 31, and the annular projections 32a and 34a. A fluid from one supply source is supplied to the pressure regions to adjust the gap between the pair of substrates 31 with its pressure.
FIG. 4 shows an apparatus as a fourth prior art apparatus. In this apparatus, upper and lower elastic members 51 and 52 are formed on a pair of substrates 31. The upper and lower elastic members 51 and 52 are clamped by upper and lower pressure plates 53 and 54. The upper and lower pressure plates 53 and 54, the upper and lower elastic members 51 and 52, and the pair of substrates 31 form upper and lower hermetic chambers U and D. Compressed air from a compressed air source 56 is supplied to the upper and lower hermetic chambers U and D through a pressure control valve 55, to press the pair of substrates 31 (see Japanese Unexamined Patent Publication No. 7-104308). If the pressures in the upper and lower hermetic chambers U and D are different from each other, they are adjusted to be always equal to each other with the function of two, first and second air operator type pressure reducing valves 57 and 58 respectively communicating with the upper and lower hermetic chambers U and D. As a result, a uniform air gap can be obtained without distorting the pair of substrates 31, while causing no warp in the substrates 31.
In the first prior art, the number of substrates that can be processed at once is limited to a pair. To process a large amount of substrates, apparatuses corresponding in number to the number of substrates are required. As a result, the apparatuses become very large as a whole, which is not suitable for mass production.
In the second prior art using the rubber sheets, when the rubber sheets are inflated with the fluid, they do not inflate in parallel to the substrates but inflate like a convex lens. As a result, a pressure is applied to the substrates only locally, and the cell gap becomes nonuniform.
Furthermore, in the third and fourth prior arts, the number of substrates that can be processed at once is limited to a pair. To process a large amount of substrates, apparatuses corresponding in number to the number of substrates are required. As a result, the apparatuses become very large as a whole, which is not suitable for mass production.